Bell Canada defended itself this week against accusations it was mining too greedily and too deep into customer information in order to show more targeted advertising — but aside from privacy concerns, it’s still not clear how the program will work.

The telecom’s new privacy policy, coming into effect Nov. 16, would let it track subscribers’ phone calls, location, web history, app downloads and even TV viewing habits, all in order to create detailed profiles for advertisers seeking specific demographics to pitch their products to.

The scheme has, understandably, alarmed privacy advocates.

Not only do Bell’s Internet, cable and wireless businesses give it a staggering amount of information on the tastes and habits of its customers, but the data could prove too enticing for authorities looking for dirt on Canadians.

“This is an open invitation for law enforcement to know that they’ve got one of the most detailed customer profiles possible in the country,” consumer rights advocate Philippe Viel warned recently.

Canada’s privacy commissioner Jennifer Stoddart was sufficiently alarmed by the proposed policy change that her office is investigating it for possible breach of the Personal Information Protection and Electronic Documents Act.

But even if Bell’s “relevant ads” are legal, where will they actually end up? The company says the program will affect its 7.7 million mobile subscribers first, with a promise that “it won’t mean you’ll see more ads, but you’ll see better ones.”

That would seem to set it apart from similar programs by U.S. telecoms Verizon and AT&T, which rolled out their own targeted ads over the last year. In those programs, the companies might send customers emails, texts or on-screen notifications on their mobile devices, but a Bell spokesperson this week told Canada.com the “relevant ads would appear instead of random ads” while customers were surfing the web.

But does that mean Bell will replace the ads on websites with its own messages? No matter how “relevant,” that would amount to a kind of hijacking of a website’s content that few publishers would accept. Say a mobile user visits the website of Rogers-owned Maclean’s magazine and sees Bell’s ads on the site instead. Would that not be tantamount to theft?

We put the question to a company spokesperson but despite two phone calls and a promise to follow up via email, Bell was unable to answer how the mobile ads would work and whether they would swap out existing ads online.

But perhaps the better question isn’t how but rather why Bell is suddenly so interested in advertising.

In a statement issued Wednesday, Bell Mobility President Wade Oosterman said the “new program puts Bell in a position to compete with world players like Google, Facebook and others in focused online information delivery.” But those companies provide free services in exchange for being able to show you ads. Bell, on the other hand, already charges subscribers for its service. Customers pay for access to the Internet with the expectation that it won’t be tinkered with.

That Bell is responding to privacy concerns by comparing itself to Google and Facebook, two companies notorious for indiscriminately gobbling up user data, is all the more troubling.